Studies are proposed to relate chemical structure to acute toxicity, to in vitro effects on isolated muscles and to immunological characterists of the many neurotoxins present in venom from the scorpion Centruroides sculpturatus. Acute toxicities of each of the 14 different neurotoxins present in the venom will be determined. In vitro dose response studies of the effects of each toxin in muscle preparations innervated by cholinergic and by adrenergic nerves will be carried out. Studies will be undertaken to demonstrate the degree of cross reactions of each of the toxins to specific antisera produced by immunizing rabbits with each respective toxin. Toxin neutralizing powers of specific sera will be determined for each of the toxins in relation to whole venom, the specific toxin and cross reacting toxins. Preliminary investigations to relate the degree and nature of chemical modification of the toxins to their respective biological and immunological characteristics will be obtained.